The frog has proved an invaluable "biological robot" because, when stimulated visually, it may exhibit complex patterns of behavior which reflect a subtle analysis of the environment. It has thus served as a testbed for studies of pattern recognition, depth perception, cooperative computation, obstacle avoidance, and simple forms of learning. We study visuomotor coordination in frog and toad at two levels: a) to analyze what schemas (information processing "modules") are employed in actual brains; b) to model how schemas are implemented in living neural networks. Here a central theme is the analysis to tectal circuitry. Results of this proposed study will lead to a better understanding of sensorimotor integration in vertebrates and the computational techniques with which neural function can be understood. We have made interaction with experimentalists an integral part of our research to date; we now propose to augment these interactions by work in our own laboratory in which collection of new data is closely integrated with modeling. In particular, we will study prey-catching, predator-avoidance and other natural behaviors of frog and toad, both with and without lesions, in a richly structured environment. This will yield models at the level of interacting schemas. Each schema will provide constraints on the neural circuitry within a given brain region. Models meeting these constraints will be tested both neuroanatomically and neurophysiologically.